Author: hselasky
Date: Fri Oct 30 14:50:29 2015
New Revision: 290195
URL: https://svnweb.freebsd.org/changeset/base/290195

Log:
  Reduce the DWC OTG interrupt load by not reading all the host channel
  status registers for every interrupt. Check a common host channel
  status interrupt register first, then conditionally read the
  individual host channel status registers.
  
  Submitted by: Sebastian Huber <[email protected]>
  MFC after:    1 week

Modified:
  head/sys/dev/usb/controller/dwc_otg.c

Modified: head/sys/dev/usb/controller/dwc_otg.c
==============================================================================
--- head/sys/dev/usb/controller/dwc_otg.c       Fri Oct 30 13:05:39 2015        
(r290194)
+++ head/sys/dev/usb/controller/dwc_otg.c       Fri Oct 30 14:50:29 2015        
(r290195)
@@ -2558,6 +2558,7 @@ dwc_otg_interrupt_poll_locked(struct dwc
        struct usb_xfer *xfer;
        uint32_t count;
        uint32_t temp;
+       uint32_t haint;
        uint8_t got_rx_status;
        uint8_t x;
 
@@ -2575,14 +2576,18 @@ repeat:
                DPRINTF("Yield\n");
                return;
        }
+
        /* get all host channel interrupts */
-       for (x = 0; x != sc->sc_host_ch_max; x++) {
+       haint = DWC_OTG_READ_4(sc, DOTG_HAINT);
+       while (1) {
+               x = ffs(haint) - 1;
+               if (x >= sc->sc_host_ch_max)
+                       break;
                temp = DWC_OTG_READ_4(sc, DOTG_HCINT(x));
-               if (temp != 0) {
-                       DWC_OTG_WRITE_4(sc, DOTG_HCINT(x), temp);
-                       temp &= ~HCINT_SOFTWARE_ONLY;
-                       sc->sc_chan_state[x].hcint |= temp;
-               }
+               DWC_OTG_WRITE_4(sc, DOTG_HCINT(x), temp);
+               temp &= ~HCINT_SOFTWARE_ONLY;
+               sc->sc_chan_state[x].hcint |= temp;
+               haint &= ~(1U << x);
        }
 
        if (sc->sc_last_rx_status == 0) {
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